Unable to reinstall OSX Mountain Lion

If I were you, I would just go to the App Store and redownload Mountain Lion from your "Purchases" tab. After it downloads it will try to install. Quit the installation at that point and have a 8GB+ USB flash drive handy and use Lion DiskMaker to make a bootable installation drive that you'll be able to use again should the need arise.

Then you can boot from the USB flash drive and reinstall Mountain Lion.

Good luck,

Clinton

Edit; Sorry, I missed the part that stated that you wanted to downgrade to Lion - the only way I know to to that is if you've a machine that shipped with Lion. You should be able to go to Internet Recovery (Command, option, R keys held down whilst booting) and erase your drive and reinstall Lion - if that's what your computer shipped with.

Message was edited by: clintonfrombirmingham

You can't boot to your OSX startup disk? Only your Recovery partition? Try holding down the option key whilst booting and see if you can select your startup disk...

Clinton

If the installation is failing, your boot disk may be damaged. Open Disk Utility and - if it can find the startup partition - try verifying and, if needed, repairing the partition. If that doesn't work, your hard drive may be dying, with only the small Recovery parition intact.

Your only other choice - and this is if Disk Utility can see the startup partition - is to erase the drive using Disk Utility and format it as "Mac OS Extended (Journaled)" with a single GUID partition. This will wipe all data from your hard drive, so I'm hoping that you have a backup? After erasing and formatting the drive, try installing the OS again.

That's about as good as it gets - if everything fails, then your hard drive is likely dead and you'll need to replace it.

Good luck,

Clinton

If Disk Utility is 'seeing' the drive "Macintosh HD" then you should be able to hold down the option key and select it as the startup disk - unless the OS is damaged on it, of course. Of course, you should be able to directly reinstall OS X from the Recovery partition, as well.

I don't know what else to tell you - you may have to take your machine into your local Apple Store or an AASP (I wouldn't take it back to Best Buy, if you can help it: I've found those people to be idiots) and have them boot the machine and try reinstalling OS X via a USB flash drive.

Sorry that I couldn't be of more help...

Clinton

Not every mac is eligible for an internet recovery:

http://support.apple.com/kb/HT4904

I was trying to do a clean install, and had this error over and over, but then I found this video that worked just perfectly for me.

My computer was with a date of 2000.

Fixed it through the Terminal and it worked =D

https://www.youtube.com/watch?v=Cf4TzZt24-M

I was experiencing the same thing while attempting to reinstall OSX Lion. The method described in the YT video worked. Thanks!